A multicarrier transmission system where communication is carried out using a plurality of frequency carriers, frequency scheduling is performed taking into account the frequency selectivity of multipath fading channels to improve throughput.
For efficient uplink frequency scheduling, abase station needs to learn the received qualities of all resource blocks (hereinafter simply “RB's”) in all mobile stations and so all mobile stations need to transmit reference signals using all RB's. A reference signal refers to a known signal set in advance between the base station and the mobile stations or a signal according to this known signal. Further, a reference signal is also referred to as a “pilot signal.”
FIG. 1 shows a conventional scheduling method. The base station measures the received quality of each RB using the reference signals transmitted from mobile stations A and B and assigns RB's for data transmission to mobile stations A and B based on the received qualities (see, for example, Non-Patent Document 1).    Non-Patent Document 1: “Investigations on Packet Scheduling Exploiting Frequency Selectivity in Uplink Radio Access,” Yoshiaki Ofuji, Akihito Morimoto, Kenichi Higuchi, Mamoru Sawahashi, the Institute of Electronics, Information and Communication Engineers Society Conference, B-5-51, pp 451, March 2005.